1. Field of the invention
The present invention concerns a vehicle seat and, more in particular, it relates to a method of manufacturing a vehicle seat comprising a cushioning pad and a skin material covering the cushioning pad in which the cushioning pad and the skin material are integrated by means of adhesives.
2. Description of the Prior Art
In manufacturing a seat by using adhesives, a skin material and a cushioning pad are disposed between upper and lower dies, and bonded integrally by interposing adhesives between the skin material and the cushioning pad. Hot-melt adhesive in the form of an adhesive film or solvent type adhesives have been used for the adhesives.
In the case of using the hot-melt type adhesives, a high heat resistance is required for the skin material and the cushioning pad and, in addition, there is a problem that a thermal load is applied to the skin material and the cushioning pad since a higher temperature is required for melt-bonding of adhesives. In a case of using the solvent type adhesives, since adhesion is formed already upon coating the adhesive, it has been a problem that the cushioning pad and the skin material are bonded at the stage of contact.
For overcoming the foregoing problems, a technique of using reactive hot-melt adhesives has been proposed (for example, refer to Japanese Patent Laid Open No. 68391/1991).
Also in the technique proposed above, bonding between the skin material and the cushioning pad in the production of the seat has been conducted in the same way as in the prior art, by using upper and lower dies, disposing the skin material conforming to one of the dies while disposing the cushioning pad on the other of the dies correspondingly, coating adhesives at least on one of the opposing surfaces of the cushioning pad and the skin material, applying pressure and heating and, further, applying cooling to the side of the skin material.
When the skin material and the cushioning pad are disposed in the separate upper and lower dies in this way for the bonding between the surface layer and the cushioning pad, attachment of the cushioning pad to the die and that of the skin material to the die have to be conducted separately in the bonding step of the skin material and the cushioning pad. Further, if the skin material and the cushioning pad are disposed separately to the upper and the lower dies, respectively, as described above, it is necessary that one of the upper die and the lower die is cooled simultaneously with heating so as to make the molding cycle satisfactory. However, application of heating and cooling by the identical die after bonding the skin material and the cushioning pad results in heating or cooling of the identical tie itself, which makes the molding cycle longer and increases the production time. Further, since the cushioning pad and the skin material are heated, cooled and press-bonded by the identical die, this causes fluffs in the raised skin material.